Skin and soft tissue infections Flashcards
1
Q
Clinical syndromes caused by staphylococcus aures
A
Folliculitis Furuncles Carbuncles Impetigo Cellulitis Toxic shock syndrome Post-operative wound infections
2
Q
Clinical syndromes caused by streptococcus pyogenes
A
Impetigo Erysipelas Cellulitis Necrotising fasciitis Toxic shock syndrome
3
Q
Impetigo
A
- very superficial infection involving the epidermis
- commonest in children and is usually on the face often around the mouth and nose
- two forms
4
Q
What are the two forms of impetigo?
A
- non-bullous (‘honey-crust’) lesions, most commonly due to Strep pyogenes (Group A strep)
- bullous, when bullae rupture they appear instead as thin ‘varnish’like’ crusts due to staph aureus
5
Q
Folliculitis
A
- infection of the hair follicles
- may occur after exfoliation, use of a loofah sponge, shaving or spontaneously
- whirlpool (hot tub or spa) folliculitis can be caused by pseudomonas aeruginosa
- self-limiting so there is no specific treatment
6
Q
Abcesses and furuncles
A
- staph aureus is the leading community pathogen causing abcesses and furuncles
- certain phage types are associated with recurrent episodes of furunculosis and may spread among family members
- staphylococcal blood stream infection from a minor skin lesion or a furuncle may rarely result in severe complications, including osteomyelitis, septic arthritis and endocarditis
7
Q
What’s an abcess?
A
A collection of pus in any tissue
8
Q
What’s a furuncle?
A
An abcess in the skin, commonly called a boil
9
Q
What’s a carbuncle?
A
Larger abcesses, interconnected furuncles
10
Q
What is cellulitis and what are the 3 categories?
A
Acute spreading inflammation involving soft tissues but excluding muscle.
- Erysipelas
- Acute cellulitis
- Necrotising fasciitis
11
Q
Erysipelas
A
- involve the superficial dermis
- extremes of age
- usually Group A strep (but can be group G, B, C)
- face and leg commonest sites
- distinction from acute cellulitis is unimportant clinically
- blood cultures, aspirates, biopsies are usually negative
- may recur in the same area (possibly related to local lymphatic insufficiency)
12
Q
Treatment of erysipelas
A
Benzyl penicillin (iv) High does iv flucloxacillin will cover both strep and staph infection if doubt about aetiology
13
Q
Acute cellulitis
A
- ‘wild fire’ onset
- often high fever then cellulitis 12 hours later
- rapidly spreading inflammation of the deep dermis and subcutaneous fat.
- often subtle portal of entry
- usually group A strep (sometimes staph aureus)
- redness and pain, systemic signs and symptoms
- lymphangitis can occur (streak of redness on lymphatics)
- blood cultures/aspirates usually negative unless there is a purulent collection
14
Q
Necrotising fasciitis
A
- life threating
- involves superficial fascia and underlying fat
- two main bacterial causes: strep pyogenes and synergistic infections with anaerobic organisms mixed with aerobes (abdo surgery or perineal infection/trauma)
15
Q
When would you suspect necrotising fasciitis instead of cellulitis?
A
- nec fasc failure to respond to antibiotics
- marked pain
- very unwell
- in mixed infection there could be crepitus or a foul smell
